Bistable electromagnetic valve

ABSTRACT

Proposed herein is a bistable electromagnetic valve ( 1 ) with a valve chamber ( 15 ) arranged between two pole pieces ( 5, 6 ) and a valve body ( 12 ) displaceable therein between two end positions, which is designed as a magnet armature for at least one permanent magnet ( 9, 10 ) and for at least one control coil ( 3 ), which is distinguished by a particularly compact design and low production expense. This is achieved according to the invention by arranging at least one permanent magnet ( 9, 10 ) inside the valve housing ( 2 ).

[0001] The invention relates to a bistable electromagnetic valve according to the preamble to claim 1.

[0002] Values of this type are used, for example, in refrigerant circuits of the kind described in publications DE 37 18 490 or EP 10 54 200.

[0003] In such valves, a bistable situation is achieved by arranging permanent magnets outside the valve housing, next to the valve chamber or next to the pole pieces, so that the valve body has two end positions at the pole pieces, in which it is held by these permanent magnets.

[0004] In one design, known valves have a control coil arranged in the axial extension of a pole, thereby resulting in different forces of attraction for the two end positions of the valve body upon activation of the control coil. Another known layout of the control coil is laterally situated next to the valve chamber, which yields a uniform distribution of forces of attraction for the control coil on the valve body in both end positions, but the dimensions of the permanent magnets must be comparatively large due to a lacking, or at least not closed, magnetic return sheet, which results in a corresponding manufacturing expense.

[0005] The object of the invention relative to the described prior art is to propose a valve with a compact design that is inexpensive to manufacture.

[0006] This object is achieved in a valve according to the preamble to claim 1 with the characterizing features.

[0007] The measures specified in the subclaims enable advantageous embodiments and further developments of the invention.

[0008] Consequently, a valve according to the invention is characterized by the fact that at least one permanent magnet is arranged inside the valve chamber. In this case, contact between the permanent magnet and the fluid streaming through the valve is accepted. The advantage to this arrangement, however, is that the permanent magnet is situated in direct proximity to the valve housing or pole piece, and hence can be made smaller.

[0009] In a special embodiment of the invention, the design can here be made so compact that the valve chamber fits completely inside the control coil. In addition to the simple introduction of magnetic lines of force for the control coil in the axial direction of the valve chamber, this also yields additional advantages.

[0010] For example, the complete valve can be secured to the respective site using the already provided attachment elements of the control coil.

[0011] In a further development of the invention, at least two permanent magnets are provided, arranged spaced apart in an axial direction. This makes it possible to increase the stability of the two end positions of the valve body via higher forces of attraction of the permanent magnets, and hence to also improve the tightness of the valve in the respective position.

[0012] In a special embodiment of the invention, the selected polarization direction of the permanent magnet is parallel to the direction of movement of the valve body. This polarization direction further improves the stability of the end positions of the valve body.

[0013] In another further development of the invention, this polarization direction also enables the use of annular magnets, which envelop the respective valve seat and are aligned toward the valve chamber with the respective like pole. This embodiment can be made especially compact. In addition, the advantage to this design is that the resultant magnetic fields are rotationally symmetric relative to the middle axis of the valve, which yields a good axially parallel attraction of the valve body designed as a magnet armature.

[0014] In a further development of the invention, these annular magnets can be slipped onto the respective pole piece, which preferably exhibits an annular shoulder in the area of the seal seat for this purpose. The respective annular magnet can therefore be mounted by simply being slipped onto the accompanying pole piece until it hits the annular shoulder.

[0015] A spacer ring is preferably also provided, which defines the distance between the permanent magnets, and hence between the pole pieces. The spacer ring can therefore be used to precisely position the pole pieces and the permanent magnets relative to each other by simply joining them together, and then fix them in place inside the valve housing.

[0016] The valve body is advantageously designed as a sphere. A spherical valve body can be tightly fitted directly onto an accompanying seal seat, e.g. a conical seat, without any additional closure elements being required on the valve body.

[0017] In embodiments based on prior art, separate spheres were secured as sealing elements to a valve body with correspondingly larger dimensions. Designing the valve body as a sphere not only gives the valve body a smaller structural shape, but also provides for a good mobility of the valve body, with as little rubbing against the valve chamber as possible, as well as for good centering, e.g., in a spherical seal seat.

[0018] The slight mass of the spherical valve body also lowers the impact pulse of the valve body on the seal seat, thereby resulting in less noise generation and a distinctly longer service life for the valve. The decreased load on the valve seat lessens the requirements, and hence the complexity, associated with its production. If necessary, the valve seat or pole piece enveloping the valve seat does not even have to be hardened.

[0019] The valve body, in particular a spherical valve body of the kind described above, is advantageously guided using a guide ring inside the valve chamber, which provides the valve body with an external guide. In a special further development of the invention, the guide ring can simultaneously be designed as a spacer ring for the permanent magnet(s).

[0020] A filter element is also advantageously provided to keep dirt particles away from the seal seat, which otherwise might end up resulting in malfunctions. Stringent requirements are placed on tightness above all in refrigerant circuits, while the introduction of dirt particles, e.g. during soldering procedures or other operations, cannot be entirely avoided during the assembly of these refrigerant circuits. Since dirt is only introduced during production stages, a filter element with a capacity sufficient for the one-time cleansing of fluid in the closed circulation system can prevent the contamination of valve seats for a long time.

[0021] In a particularly advantageous embodiment of the invention, the filter element is simultaneously designed as the guide ring for the valve body. In addition, the filter element can also be designed as a spacer ring between the permanent magnets. In both structural designs, the number of required valve components is reduced.

[0022] In a particularly advantageous further development of the invention, a single component is simultaneously designed as a spacer ring, guide ring and filter element, so that all three functions can be performed by a single component, thereby minimizing the number of components for these functions.

[0023] The valve housing is preferably designed as a circular tube. A circular tube is particularly easy to incorporate into a control coil, which usually exhibits a cylindrical passage. If necessary, adapter sleeves can be provided on the outside for this purpose, to precisely center the circular tube housing without play inside the control coil, and improve, i.e. increase, the magnetic flux of the control coil.

[0024] In addition, a circular tube housing offers a cylindrical internal wall, on which flatly sealing bonds, e.g., to a pole piece or other components, can be established.

[0025] The valve housing is also preferably designed as a single piece, so as to avoid bonding sites with the resultant tightness problems and inspections. In combination with a circular tube housing, this yields a particularly simple one-piece structural shape, in which only connecting tubes must be attached on the end side, for example. The connecting tubes can here be soldered in, or injected or attached on the valve housing using other known joining methods.

[0026] At least one pole piece is advantageously provided with one or more fluid channels outside the valve axis or outside the range of action of the valve body, thereby resulting in a constant connection between the inside of the valve chamber, where the valve body is located, and the corresponding valve coupling on the side of this pole piece. This connection between the accompanying coupling and the valve chamber is never influenced by the motion of the valve body. The specified fluid channel(s) can here be provided outside or inside the pole piece (e.g., using holes or the like).

[0027] Several peripherally distributed fluid channels are advantageously provided to achieve a uniform flow into the valve chamber, and hence defined flow conditions and a defined flow resistance of the valve.

[0028] In a further development of this embodiment, a pole piece is provided with a noncircular cross-section, so that the fluid channel or fluid channels are formed by the resultant interspaces between the pole piece and interior wall of the valve housing.

[0029] In one possible embodiment for these fluid channels, an initially cylindrical pole piece is provided with external smoothened surfaces, so that areas still continue to arise between the resultant fluid channels where the pole piece abuts tightly against the interior wall of the valve housing, as a result of which the pole piece sits centrally in the valve housing.

[0030] In another advantageous embodiment of the invention, the fluid channels are routed by the permanent magnets. This is ensured in particular in an embodiment where one or more annular magnets are provided, along with externally guided fluid channels. The inflow of fluid to the one or several permanent magnets provides an additional filtration effect by holding back magnetic particles on the permanent magnet.

[0031] In particular in the structural design described above with annular magnets and spacer sleeve, the valve can be assembled by joining together the entire arrangement comprised of two pole pieces, spacer sleeve and spherical valve body, and then attaching and press molding and/or soldering it inside a tube. The press molding and/or soldering can here simultaneously produce a sealing function between one pole piece and the housing, wherein a large contact surface is preferably provided between the housing and the pole piece to be tightly attached, in particular when press molding.

[0032] If necessary, sealing elements, e.g., elastomers, Teflon or the like, can be provided for this purpose.

[0033] Other advantages can be realized by pressing in an external bead. For example, tight-fitting internal structural components can be fixed in place in an axial direction by one or more of these beads.

[0034] The guide, filter and/or spacer ring is preferably designed to allow fluid through in both the axial and radial directions. This yields various advantages, in particular in conjunction with fluid channels along the interior wall of the housing.

[0035] On the one hand, this ensures that the valve chamber is completely and uniformly loaded with fluid even though the individual annular structural elements are joined tightly together. On the other hand, given two annular magnets, the fluid flows toward both annular magnets, thereby improving the magnetic filtration effect relative to magnetic dirt particles. In addition, this provides for a thorough and uniform flow through the filter ring, thereby ensuring that the filter ring is exposed to a uniform load of dirt particles.

[0036] In a further development of the invention, an external coarse filter can also be provided, e.g. a sieve insert, which is placed inside the tubular housing.

[0037] The valve according to the invention can be designed as a so-called 2/2-way valve. In this case, a through hole is provided in only one pole, emptying out in a seal seat on the valve chamber side. This pole piece is preferably tightly bonded on the outside with the valve housing, e.g., press molded or soldered. The other pole piece exhibits the fluid channels described above, so that fluid can continuously be relayed to the valve chamber over the side of this pole piece. The spherical valve armature exhibits two stable end positions, one at each of the two pole pieces, wherein the valve seat of the through hole of the one pole piece is either closed or opened.

[0038] In order to achieve a symmetrical arrangement and, even with the valve open, a well centered position of the spherical valve armature, a corresponding blind hole with a conical seat corresponding to the seal seat can be introduced in the pole piece opposite the seal seat.

[0039] The invention can also be designed as a so-called 3/2-way valve. To this end, both pole pieces are to be provided with a corresponding through hole and a respective valve seat. In pole pieces with outside fluid channels, a central tube is here preferably inserted in a hole of the pole piece situated in an extension of the through hole and tightly bonded there, e.g. press molded or soldered. If necessary, a sealing element can here also be provided between the central tube and the pole piece.

[0040] In the embodiment described above, the central tube is taken out of the valve housing on the coupling side, and there bonded to the housing, e.g. press molded or soldered. This central tube can then be used directly as a connecting tube for the fluid circuit, e.g. the refrigerant circuit. This central tube can simultaneously be fixed relative to the valve housing in both a radial and axial direction in a single assembly procedure, e.g. by press molding or soldering.

[0041] Given the right diameter configuration, an intermediate space is situated between the exterior wall of the central tube and the interior wall of the valve housing, and connected with the valve chamber via the outside fluid channels. This intermediate space is coupled with an inflow line in the case of a 3/2-way valve, e.g., by inserting a tube line into a corresponding hole of the valve housing and tightly bonding it there, e.g., through soldering.

[0042] In a special embodiment of the invention, a T-shaped or Y-shaped tubular housing is provided from the very outset before the internal structural components are assembled. The two pole pieces with an annular magnet and guide, spacer or filter ring and, if necessary, sealing elements, can here be introduced together with the central tube into the tube housing, and fixed in a single assembly procedure. Only the coil then still has to be slipped over the straight, continuous portion of the tubular valve housing, and the valve is completed.

[0043] An exemplary embodiment of the invention is shown on the drawing, and will be described in greater detail below based on the figures.

[0044] Shown on:

[0045]FIG. 1 is a longitudinal section through a 2/2-way valve according to the invention, and on

[0046]FIG. 2 is a longitudinal section through a corresponding 3/2-way valve.

[0047] Valve 1 according to FIG. 1 encompasses a tubular valve housing interspersed with a control coil 3. Adapter pieces here ensure the good fit and increased magnetic flux of the control coil of the valve housing 2 in the control coil 3 given deviations in the outside diameter of the valve housing 2 from the inside diameter of the control coil 3.

[0048] The internal structural components of the valve 1 are situated inside the valve housing 2 in the area of the control coil 3.

[0049] Specifically, these are two pole pieces 5, 6 whose inner ends each exhibit an annular shoulder 7, 8. Two permanent magnets 9, 10 designed as annular magnets are slipped onto the pole pieces 5, 6 until they hit the stop at the annular shoulders 7, 8. Placed between the permanent magnets 9, 10 is a spacer ring 11, which simultaneously serves as the filtering element and guide ring for a spherical valve body 12. The valve body 12 is made out of a magnetic or magnetizable material, and hence used directly as the valve armature.

[0050] The pole piece 5 incorporates a through hole 13 that empties out in what is here a spherical valve seat 14, but which can also be designed differently, e.g. as a conical seat, inside the valve chamber 15. The opposing pole piece 6 exhibits only a blind hole 16 with a spherical seat 17 on the end side, which can also be differently designed, e.g. as a spherical seat, for the valve body 12.

[0051] The outside of the pole piece 6 is provided with smoothened surfaces 18, thereby forming fluid channels 19 between the pole piece 6 and the valve housing 2 at this location.

[0052] All internal structural elements of the valve 1 are press molded between two peripherally running beads 20, 21 in the valve housing 2, and hence fixed in the axial direction.

[0053] Accommodated on the end side of the valve housing 2 are two connecting tubes 22, 23, with which the valve can be connected to the respective fluid circuit. In this exemplary embodiment, the connecting tubes 22, 23 are molded onto the valve housing 2 as a single piece, so that this location has no bonding site, and hence no sealing problems.

[0054] The fluid is supplied to the valve 1 according to FIG. 1 via the connecting tube 23. The fluid passes through the fluid channels 19 between the pole piece 6 and the valve housing 2 and enters into the area of the valve chamber 15. It here first flows on the outside along the permanent magnet 10, and then gets into the spacer ring 11, which is permeable in both the radial and axial directions. As a result, the flow also passes to the opposing permanent magnet 9. The permanent magnets 9, 10 have a smaller outside diameter relative to the inside diameter of the valve housing 2, so that sufficient space remains between the permanent magnets 9, 10 and the valve housing 2 for the flow of fluid, and for the accumulation of magnetic dirt particles. The spacer ring 11 also serves as a mechanical filter element to trap nonmagnetic dirt particles in the fluid before they can penetrate inside the valve chamber 15. At the same time, the spacer ring 11 provides a guide for the spherical valve body 12.

[0055] In the switch setting of the valve 1 shown, the 2/2-way valve is closed, i.e. the valve body 12 rests on the valve seat 14, and seals off the through hole 13. Actuating the control coil 3 makes it possible to switch the valve body 12 to the opposite position, in which it hits the spherical seat 17, thereby opening the through hole 13 to the inside of the valve chamber 15. In this switch setting, the fluid can flow via the through hole 13 all the way to the connecting tube 22.

[0056] The permanent magnets 9, 10 are polarized in such a way as to align the respective like poles toward the inside, i.e. toward the spacer ring 11, and the corresponding other poles toward the connecting tube 22, 23. The permanent magnets 9, 10 are hence polarized in a direction parallel to the valve axis. This yields a permanent magnetic field in the area of the valve seat 14 or spherical seat 17, which holds the valve body 12 in the respective end position. The bistable configuration of the valve 1 is realized in this way.

[0057] The permanent magnets 9, 10 can be given very small dimensions by arranging them inside the valve housing 2 in direct proximity to the valve body 12. In addition, arranging the permanent magnets 9, 10 in the area of the valve seat 14 or spherical seat 17, i.e. in the area of the end position of the valve body 12, allows them to exert their forces particularly well, thereby ensuring a good sealing function or stable switch setting, even given magnets with comparatively small dimensions.

[0058] The valve arrangement according to FIG. 2 essentially corresponds to the exemplary embodiment described above. The difference is that the valve according to FIG. 2 is designed as a 3/2-way valve.

[0059] To this end, the connecting tube 23 has inserted into it a central tube 24 extending all the way to the pole piece 6, which is provided with a location hole 25 to accommodate the central tube 24.

[0060] The location hole 25 in the pole piece 6 is extended to inside the valve chamber 15 by a through hole 26. A spherical or conical valve seat 27 is accommodated in the pole piece 6 in the outlet area, which is opened or closed alternating with the valve seat 14, depending on the switch setting of the valve.

[0061] An intermediate space 29 connected to an inflow line 31 via a hole 30 results between the central tube 24 and the casing area 28.

[0062] In the embodiment shown, a sealing element 32 is also inserted into an annular groove 33 of the pole piece 5 and, as evident from an outer bead 34, press molded or soldered.

[0063] The 3/2-way valve according to FIG. 2 has an inflow line 31 and two output lines. One of the output lines is comprised of the connecting tube 22 as in the aforementioned exemplary embodiment, but the other output line is now formed by the connecting tube 23, which served as an inflow line in the 2/2 way model.

[0064] Inflow takes place via the intermediate space 29 toward the fluid channels 19. As in the aforementioned exemplary embodiment, the flow passes to the permanent magnets 9, 10 and the spacer and guide ring 11. The permanent magnets 9 and 10 here also act as magnetic filter elements to hold back the magnetic dirt particles, while the spacer and guide ring 11 is designed as a filter ring permeable to fluid in a radial and axial direction. The fluid gets inside the valve chamber 15 in this way.

[0065] The fluid can now escape either via the through hole 13 or, depending on the switch setting of the valve, via the through hole 26. In the switch position shown, the valve seat 14 is closed by the valve body 12, while the valve seat 27 is open. The fluid hence streams toward the output line 23 in this switch setting.

[0066] After a control pulse is relayed through the control coil 3 to initiate a switchover, the valve seat 27 is closed, and the valve seat 14 is opened at the same time, so that the fluid streams via the through hole 13 toward the connecting tube 22. The control coil 3 and permanent magnets 9 and 10 here operate exactly as in the aforementioned exemplary embodiment.

[0067] As illustrated by the sealing element 32, care must be taken to establish as tight a seal as possible between the one pole piece 5 and the valve casing 2. The annular sealing element used to accomplish this is only an example. Flat press molding or soldering would also be possible. This type of arrangement would correspond to the exemplary embodiment depicted based on FIG. 1.

[0068] The central tube 24 must be sealed relative to the pole piece 6 in a corresponding manner. If required, a sealing element can here also be used in a manner not shown in any greater detail. In the embodiment according to FIG. 2, the central tube 24 abuts flatly, thereby resulting in a tight seal via press molding or soldering.

[0069] As shown on FIG. 2, the central tube 24 can be fixed in both the axial and radial directions via press molding or soldering, which becomes evident based on the bead 20 abutting the central tube 24. In this case, care must be taken to ensure that the bead 20 does not abut around the entire periphery, so that a sufficient passage always remains open between the intermediate space 29 and the fluid channels 19.

[0070] The depicted embodiments represent extremely compact structural designs that can be manufactured with an exceedingly small production expense, while ensuring a reliable long-term stability given a high tightness. In particular, the reduced mass of the valve body 12 also decreases the respective impact pulse on the valve seats 14, 27, thereby resulting in a better wear resistance by comparison to previously known valves in addition to lower operating noise levels.

Reference List:

[0071]1 Valve

[0072]2 Valve housing

[0073]3 Control coil

[0074]4 Adapter piece

[0075]5 Pole piece

[0076]6 Pole piece

[0077]7 Annular shoulder

[0078]8 Annular shoulder

[0079]9 Permanent magnet

[0080]10 Permanent magnet

[0081]11 Spacer ring

[0082]12 Valve body

[0083]13 Through hole

[0084]14 Valve seat

[0085]15 Valve chamber

[0086]16 Blind hole

[0087]17 Spherical seat

[0088]18 Smoothened surface

[0089]19 Fluid channel

[0090]20 Bead

[0091]21 Bead

[0092]22 Connecting tube

[0093]23 Connecting tube

[0094]24 Central tube

[0095]25 Location hole

[0096]26 Through hole

[0097]27 Valve seat

[0098]28 Housing area

[0099]29 Intermediate space

[0100]30 Hole

[0101]31 Inflow line

[0102]32 Sealing element

[0103]33 Annular groove

[0104]34 Bead 

1. Bistable, electromagnetic valve with a valve chamber arranged between two pole pieces and a valve body displaceable therein between two end positions, which is designed as a magnet armature for at least one permanent magnet and for at least one control coil, characterized in that the permanent magnet (9, 10) is arranged inside the valve housing (2).
 2. Valve according to claim 1, characterized in that the valve chamber (15) is arranged inside the control coil (2).
 3. Valve according to one of the preceding claims, characterized in that at least two permanent magnets (9, 10) are provided.
 4. Valve according to one of the preceding claims, characterized in that the permanent magnet(s) (9, 10) is/are arranged next to a valve seat (17, 27).
 5. Valve according to one of the preceding claims, characterized in that the polarization direction of the permanent magnets (9, 10) runs in an axial direction.
 6. Valve according to one of the preceding claims, characterized in that the permanent magnet or the permanent magnets (9, 10) is/are designed as an annular magnet.
 7. Valve according to one of the preceding claims, characterized in that a spacer ring (11) is provided between two annular magnets (9, 10).
 8. Valve according to one of the preceding claims, characterized in that the valve body (12) designed as a magnet armature is spherical.
 9. Valve according to one of the preceding claims, characterized in that a guide ring (11) is provided for the valve body (12).
 10. Valve according to one of the preceding claims, characterized in that the guide ring for the valve body (12) is provided as a spacer ring (11) between the annular magnets (9, 10).
 11. Valve according to one of the preceding claims, characterized in that a filter element (11) is provided.
 12. Valve according to one of the preceding claims, characterized in that the filter element (11) is designed as a guide ring for the valve body.
 13. Valve according to one of the preceding claims, characterized in that the filter element (11) is designed as a spacer ring between the annular magnets (9, 10).
 14. Valve according to one of the preceding claims, characterized in that the valve housing (2) is comprised of a circular tube.
 15. Valve according to one of the preceding claims, characterized in that the housing (2) is designed as a single piece.
 16. Valve according to one of the preceding claims, characterized in that one or more fluid channels (19) are attached to a pole piece (6) outside the valve axis.
 17. Valve according to one of the preceding claims, characterized in that several peripherally distributed fluid channels (19) are attached to a pole piece (6) outside the valve axis.
 18. Valve according to one of the preceding claims, characterized in that a pole piece (6) exhibits a noncircular outside cross-section.
 19. Valve according to one of the preceding claims, characterized in that the fluid channels (19) situated outside the valve axis are routed past at least one permanent magnet (9, 10).
 20. Valve according to one of the preceding claims, characterized in that at least one pole piece (5, 6) is press molded or soldered with the housing.
 21. Valve according to one of the preceding claims, characterized in that at least one sealing element (32) is provided between a pole piece (5) and the valve housing (23).
 22. Valve according to one of the preceding claims, characterized in that a bead (20, 21) is provided inside the valve housing (2) to fix the internal structural elements in place.
 23. Valve according to one of the preceding claims, characterized in that the guide and/or filter and/or spacer ring (11) is designed to allow fluid through in an axial and radial direction.
 24. Valve according to one of the preceding claims, characterized in that an external coarse filter is provided.
 25. Valve according to one of the preceding claims, characterized in that it is designed as a 2/2-way valve.
 26. Valve according to one of the preceding claims, characterized in that it is designed as a 3/2-way valve.
 27. Valve according to one of the preceding claims, characterized in that a central tube is connected fluid-tight with a pole piece (6) inside the valve housing (2).
 28. Valve according to one of the preceding claims, characterized in that a sealing element is provided between the central tube (24) and the accompanying pole piece (6).
 29. Valve according to one of the preceding claims, characterized in that the tubular valve housing is designed as a T-piece or Y-piece.
 30. Refrigerating circuit for a refrigeration system, in particular with several refrigerating compartments, with a compressor, a condenser, several evaporators, which each are allocated to one of the refrigerating compartments, as well as at least one electric control valve for connecting the condenser with one or more of the evaporators based on predetermined operating modes, characterized in that the control valve (1) is designed according to one of the preceding claims.
 31. Household appliance with a refrigerating circuit, in particular a refrigerator or freezer chest, characterized in that the refrigerating circuit is designed according to claim
 30. 